Occupant restraint systems for use in vehicles are known in the art. One type of restraint system includes an actuatable inflatable restraint module which has an inflatable restraint that is commonly referred to as an air bag. The restraint module is actuated and the air bag is inflated within a vehicle passenger compartment upon the occurrence of a vehicle crash condition for which a vehicle occupant is to be restrained.
A sensor detects a parameter which is indicative of a vehicle crash condition and provides a signal indicative thereof to a controller of the system. In response to a collision-indicating signal from the crash sensor, the controller provides an actuation signal to cause actuation of the restraint module upon a determination of a deployment crash condition.
In one example, the crash sensor is an accelerometer that provides an electrical signal having a value functionally related to the vehicle's crash acceleration. Within the controller, the accelerometer's signal is sampled and an evaluation of the information contained within the sampled signal is used to determine whether the signal is indicative of a deployment crash condition.
Restraint modules having one or more adjustable aspects to enhance performance of the restraint module are also known. Such a restraint module is commonly referred to as a "smart restraint." For example, in the inflatable restraint module, the dynamic deployment profile of the air bag is adjustable. Specifically, the inflation timing, the inflation pressure, and the positioning of the inflating air bag are all known adjustable aspects. Adjustment of the restraint module is based upon sensed occupant conditions.
As occupant restraint systems become more complex, a greater number of sensors are used to sense a greater number of vehicle and occupant conditions. The great number of sensory inputs are used in algorithms to make control determinations for the restraint module. Increases in the sampling and evaluating of sensory information increases the evaluation time of the system or increases the need for a faster, more powerful, and more expensive controller. It is desirable to control sense rate and the sample rate of data and control evaluation rate of the data so that a less expensive controller can be used in the restraint system while providing the desired level of control capability.